In well drilling activity, "straight hole drilling" commonly means that whatever the direction and angle (course) of an existing well bore, that course is being maintained as the well is deepened. The expression "directional drilling" usually implies that active efforts are being made to control or change the course of a progressing well bore.
The Bottom Hole Assembly (BHA) has traditionally been selected and assembled at the surface for a specific action down hole during an entire run. In conjunction with Measurement While Drilling (MWD) equipment, the special assemblies and the related art leaves little to be desired in terms of effect. The operational costs have been high because the special assemblies require a round trip to change effect sought downhole while drilling.
With the advent of MWD equipment the demand for precision and accuracy of down hole deflecting equipment has eased because the effect being accomplished can be continually judged. With exactness demands related, apparatus that will deflect on command and remain straight on command and drill in either condition, and do so reliably is more practical.
It is therefore an object of this invention to provide apparatus controllable from the earth surface to cause the centerline of the down hole drilling assembly to be straight for drilling or deflected for drilling selectively.
It is another object of this invention to provide apparatus to cause the centerline of a down hole drilling assembly to be straight for drilling or deflected for drilling in response to the repeated application of bit loads.
It is still a further object of this invention to provide apparatus with a telescoping body with intrinsic hinge means that will deflect upon selected instances of the application of bit load in a series of instances of the application of bit load.
It is still another object of this invention to provide apparatus to cause a change in pressure at the standpipe when the downhole deflecting tool is in selected modes of operation.
These and other objects, advantages, and features of this invention will be apparent to those skilled in the art from a consideration of this specification, including the attached drawings and appended claims.